1. Field of the Invention
The present invention relates to a semiconductor device and methods forming the same, and more particularly to a DRAM device having a capacitor and a DRAM device so formed.
2. Description of the Related Art
In semiconductor devices such as Dynamic Random Access Memory devices (DRAMs), each cell is composed of a transistor and a capacitor. In DRAMs, cells require periodic reading and refreshing operations. Owing to the advantage of low price per unit bit, high integration, and capability for simultaneous read/write operations, DRAMs have been widely used in commercial applications. In the meantime, a “soft” error in the form of a loss of charge stored in a capacitor can be caused by external factors in a DRAM, thereby inducing mis-operation in the DRAM. In order to prevent such a soft error, methods of enhancing the capacitance of a capacitor have been suggested.
The capacitance of the capacitor can be enhanced by increasing the surface area of the lower electrode. Although many studies have investigated techniques for increasing the surface area of lower electrodes, technical challenges are presented in practical manufacturing processes for forming such devices due to the ever-increasing integration of semiconductor devices.